1. Field of the Invention
This invention relates generally to labyrinth seals in gas turbine engines and, more particularly, to a new and improved shield for preventing lubricant contamination of a labyrinth seal in an engine having vertical and horizontal operating modes.
2. Description of the Prior Art
In a proposed vertical take-off and landing aircraft, gas turbine engines mounted at the ends of the wings power rotors which propel the aircraft in both a cruise mode and in an ascent/descent mode. In the cruise mode the engines are oriented horizontally and in the ascent/descent mode the engines are oriented vertically. During transition between the two modes the engines pivot about a transverse axis of the aircraft. Within the gas turbine engines, labyrinth seals are employed in their usual fashion to control the flow of gases and must be shielded from dripping lubricant when the engine is oriented vertically. For example, where a shaft has a lubricated bearing inboard or forward of a labyrinth seal, a shield must be arranged between the bearing and the seal to avoid lubricant contamination of the seal. In applications involving shafts located centrally in engines, further considerations include the sequence in which the various parts are to be assembled and the clearances necessary to permit assembly while still insuring adequate shield operation. In the past, bearing and seal arrangements for vertically oriented engines have been proposed in which the downward flow of lubricant from the bearing is channeled in particular directions either to recover the lubricant or to avoid labyrinth seals. These proposals, however, lack suitability for the environment in which a shield according to this invention finds utility.